feat(ext4): directory entry find/add/remove operations

crates/servers/storage-server/src/tests/ext4.rs

@@ -342,6 +342,32 @@ fn free_block_makes_it_available_again() {
     assert_eq!(b1, b2);
 }
 
+#[test]
+fn add_and_find_dir_entry() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    assert!(fs.find_in_dir_pub(2, b"hello").is_some());
+    assert!(fs.add_dir_entry(2, b"world", 4, 1));
+    assert_eq!(fs.find_in_dir_pub(2, b"world"), Some(4));
+}
+
+#[test]
+fn remove_dir_entry() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    assert!(fs.find_in_dir_pub(2, b"hello").is_some());
+    let removed = fs.remove_dir_entry(2, b"hello");
+    assert_eq!(removed, Some(3));
+    assert!(fs.find_in_dir_pub(2, b"hello").is_none());
+}
+
+#[test]
+fn list_dir_after_add() {
+    let mut fs = Ext4::mount(format_ext4_disk()).unwrap();
+    fs.add_dir_entry(2, b"second", 4, 1);
+    let mut entries = [DirEntry::empty(); 8];
+    let count = fs.list_dir(b"/", &mut entries).unwrap();
+    assert_eq!(count, 2);
+}
+
 #[test]
 fn read_past_eof_returns_zero() {
     let mut fs = Ext4::mount(format_ext4_disk()).unwrap();